This is a Cannot Be True question so we are looking for the answer choice that directly conflicts with the information presented in the stimulus. Let's take a look at the answer choices:
(A) Could Be True since it does not conflict with any information set forth in the stimulus. All we know from the stimulus is that random mutations can make some beneficial viruses dangerous to humans.
(B) Could Be True since this stimulus does not present any information about organisms of greater complexity than viruses other than that some viruses can kill more-complex microorganisms.
(C) Could Be True. Again, the stimulus does not present any information about microorganisms that are more complex than viruses other than that some viruses can kill more-complex microorganisms.
(D) Could Be True. There could be other ways, outside of killing other viruses that are deadly to humans, that viruses are beneficial to humans.
(E) Cannot Be True. The stimulus starts off by telling us that "viruses can have beneficial effects" and presents the example of some viruses killing more-complex microorganisms, some of which are deadly to humans. As such, it must be true that some viruses that are deadly to organisms of greater complexity ARE beneficial to humans. Answer choice (E), however, states that "no virus that is deadly to organisms of greater complexity than itself is beneficial to humans." This directly contradicts the information presented in the stimulus so (E) would be the correct answer.
Hope this helps! Please let us know if you have any other questions.
singh395October 28, 2015
I don't understand how you got to the conclusion that "it must be true that some viruses that are deadly to organisms of greater complexity ARE beneficial to humans." Where is this implication?
MehranNovember 7, 2015
Thank you for your question. Please look very carefully at the first two sentences of the stimulus. The first sentence says that viruses can have beneficial effects. In support of this claim, the second sentence explains that some (viruses) kill more-complex microorganisms, some of which are deadly to humans. This means that (a) some viruses kill microorganisms that (b) can be deadly to humans. This means that it must be true that some viruses that are deadly to more-complex organisms (organisms of greater complexity) are beneficial to humans.
Hope this helps. Please let us know if you have any additional questions.
